The need for large-scale, low-cost, novel materials for the active component in nuclear detector systems has sparked an interest in optically transparent ceramic scintillators as an alternative to single crystals. Scintillator ceramics do not undergo component segregation during processing as do single crystals, and can, in general, be more heavily doped, produced in near-net shapes and scaled up to large sizes more readily than single crystal components. While it is known that point defects in single crystals significantly affect scintillation performance by creating carrier traps or introducing competitive absorption, the true effects of grain boundaries, grain size, and porosity in ceramics on scintillation performance are not well characterized.
- Using model material systems, develop a relationship between processing parameters and defect structure in transparent ceramics.
- Establish a quantitative relationship between the ceramic processing variables, defect structure, and the scintillation performance in these materials.
- Demonstrate improved scintillator performance in the materials under investigation.
- Train graduate students in detector technology and materials preparation.
Process ceramic samples of model materials with different grain sizes and dopant concentrations using varied processing conditions. Analysis of ceramic samples through:
- Optical characterizations (optical microscopy, optical tomography, & coherent-light transmission)
- Optical spectroscopy (life time, emission, absorption, confocal microscopy)
- Microstructure investigation (SEM, TEM, EDS)
- Dopant dispersion characterization (EDS, AES, confocal microscopy)
- Characterization of lattice defects (TEM, EPR)
- Characterization of depth, concentration, and chemical nature of charge carrier traps (thermo-luminescence, X-Ray EPR)
- Scintillation characterization (radio-luminescence, decay, pulse height spectroscopy)
Title:
Control of Grain Boundaries and Defects in Nano-engineered Transparent Scintillator Ceramics for Radiological and Nuclear Applications
Sponsor:
Defense Threat Reduction Agency/BCR/DOD
Program Effective Dates:
November 2006 to November 2011
Principal Investigator:
Prof. Robert S. Feigelson, Dept. of Material Science & Engineering and Geballe Laboratory for Advanced Materials. (Stanford University)
Staff:
Dr. Romain Gaume (Stanford University)
Students:
Stephen Podowitz (Stanford University)
Collaborators:
Dr. Edith Bourret (Lawrence Berkeley Laboratory)
Dr. Stephen Payne, Dr. Nerine Cherepy (Lawrence Livermore National Laboratory)
Paul Cutler, Prof. Chuck Melcher (University of Tennessee-Knoxville)
Prof. Nancy Haegel (Naval Postgraduate School)
Prof. Nancy Giles, Prof. Larry Haliburton (West-Virginia University)